Optical transmitters/combiners can be used for the transmission of broadcast and narrowcast optical signals in a communication network. Communication networks can include CATV, FTTH (Fiber to the Home) and FTTC (Fiber to the Curb). A communication network can consist of a large number of optical transmitter/combiners, nodes, and distribution networks between the nodes and the end users. Communication networks can be used to transmit one or more optical broadcast signals to a large number of nodes and one or more narrowcast optical signals can be transmitted to smaller number of nodes or a specific node. Splitters can be used to distribute broadcast optical signals to the inputs of a plurality of optical transmitters/combiners. An optical transmitter/combiner can have one or more inputs for narrowcast or broadcast signals and can produce one or more outputs where the narrowcast and broadcast signals can be combined. The combining of narrowcast and broadcast signals can produce a reverse leakage from the narrowcast signal input to the broadcast signal input. The reverse leakage can cause a fraction of the narrowcast signal being present at the broadcast signal input of other optical transmitter/combiners resulting in a combination of the intended signals and the fraction of the unwanted narrowcast signal. The reverse leakage of the narrowcast signal can be reduced by providing sufficient isolation between the broadcast and narrowcast inputs of the transmitter/combiner.